Reading and Discussion 12&13: Encodings and Layout

by Mike Gleicher on February 15, 2015

Reading and initial posting due: Monday, March 2, 11:59pm

Turn-in link: Reading 12 on Canvas

Color is only one of the visual variables. Now we can consider the rest. Except that two of them (the two spatial dimensions, X and Y) are a huge topic unto themselves.

The starting point for this discussion is Munzner Chapter 5 (which you should have read already). You might want to scan through it a bit.

The other starting point would be to read some of Bertin’s original introduction of the concept of the visual variables. But, I don’t have a good reading of that. I haven’t read the original myself (yet).

For this week, there will be a set of readings about two slightly disjoint topics:

  1. What are the different encodings, and what do we know about their properties? (and how do we know it) – This is the world of Graphical Perception, which is experiencing a resurgence in visualization.
  2. How do we deal with the position dimensions? This starts to get at layout.

For Monday, March 2, do all of the following:

  • If you’re a 638 student, pick any one from 1-3 (you may pick more). If you’re an 838 student, read #3 and either 1 or 2.
  • Read #4 Munzner chapter 7. (and optionally skim Ch. 8)
  • Read #6 Ware, chapter 3. I was going to say this can be for Thursday, but it goes well with the others since it gets at the machinery involved.
  • Read #7 Tufte (OK, this one can be for Thursday)

Yeah, this is more than I wanted to give in one reading – but to make up for it, there won’t be a reading for March 4. (I just couldn’t decide how to divide it up!)

For the discussion… Please make an initial posting by Monday, March 2. I don’t have a good concrete prompt here but…

These readings basically express the idea of “how do I map my data to marks on the page” (where do those marks go, what color, form, … do they have, …). In a sense all visualization might be mapped to this (at least making static visualizations). What I hope is forming in your head is that there is a principled way to figure what mappings are more or less appropriate. Discuss this – how are these pieces all fitting together? how do standard designs emerge as solutions? What kinds of things don’t fit in?

The readings:

You need to experience where the whole graphical perception thing got started. There are different versions of the paper, you may read either one.

  1. (short) Cleveland and McGill. Graphical Perception and Graphical Methods for Analyzing Scientific Data. Science 229(4716), 1985.  (online library)
  2. (long) Cleveland and McGill. Graphical Perception: Theory, Experimentation, and Application to the Development of Graphical Methods. Journal of the American Statistician, 79(387) 1984.  (online library)

Jeff Heer and Michael Bostock re-created these results using crowdsourcing (many more participants, but much higher variance for several reasons). This paper is nice for many reasons, but a relevant one is that it’s a more modern presentation of (basically) the same results.

  1. Crowdsourcing Graphical Perception: Using Mechanical Turk to Assess Visualization Design. Jeffrey Heer, Michael Bostock ACM Human Factors in Computing Systems (CHI), 203–212, 2010  PDF (607.4 KB) | Best Paper Nominee

Normally, I’d pick a few other experimental papers to add, but we’ll get to those later in the semester. For now, just know that there are a lot more experiments helping us understand encodings.

For Layout, there are two chapters in Munzner (the third layout chapter we’ll get to when we talk about graphs), a Chapter in Ware, and a Chapter of Tufte (which is short).

  1. Chapter 7 “Arrange Tables” – in Munzner VAD
  2. Chapter 8 “Arrange Spatial Data” in Munzner – actually, for our purposes, we can summarize this chapter in one sentence for now “sometimes, you want to map position to position.” – we’ll come back to this chapter later. But you might want to scan through it now.
  3. Structuring 2 Dimensional Space – Chapter 3 of Visual Thinking for Design by Colin Ware. (the textbook, available online).
  4. Layering and Separation, Chapter 3 of Envisioning Information by Tufte. (in protected reader beware 14Mb file).
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